01: ////////////////////////////////////////////////////////////////////////////////
02: // checkstyle: Checks Java source code for adherence to a set of rules.
03: // Copyright (C) 2001-2007 Oliver Burn
04: //
05: // This library is free software; you can redistribute it and/or
06: // modify it under the terms of the GNU Lesser General Public
07: // License as published by the Free Software Foundation; either
08: // version 2.1 of the License, or (at your option) any later version.
09: //
10: // This library is distributed in the hope that it will be useful,
11: // but WITHOUT ANY WARRANTY; without even the implied warranty of
12: // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13: // Lesser General Public License for more details.
14: //
15: // You should have received a copy of the GNU Lesser General Public
16: // License along with this library; if not, write to the Free Software
17: // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18: ////////////////////////////////////////////////////////////////////////////////
19: package com.puppycrawl.tools.checkstyle;
20:
21: import java.util.Properties;
22:
23: /**
24: * Resolves external properties from an
25: * underlying <code>Properties</code> object.
26: *
27: * @author lkuehne
28: */
29: public final class PropertiesExpander implements PropertyResolver {
30: /** the underlying Properties object. */
31: private final Properties mProperties;
32:
33: /**
34: * Creates a new PropertiesExpander.
35: * @param aProperties the underlying properties to use for
36: * property resolution.
37: * @throws IllegalArgumentException indicates null was passed
38: */
39: public PropertiesExpander(Properties aProperties) {
40: if (aProperties == null) {
41: throw new IllegalArgumentException("cannot pass null");
42: }
43: mProperties = aProperties;
44: }
45:
46: /**
47: * {@inheritDoc}
48: */
49: public String resolve(String aPropertyName) {
50: return mProperties.getProperty(aPropertyName);
51: }
52: }
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